I am using MLA 7th edition. I am citing an article published April 10th and edited April 12th. Which date should I cite? Thank you!
With an electronic source, the purpose of providing "Date Accessed" is to avoid confusion in articles that might be edited in an ongoing fashion. As long as you provide the date you accessed the article, as well as the original publication date, you should be adhering to MLA rules.
So in your case, I would cite the publication date as April 10th and the Date Accessed as whenever you accessed it (of course). Someone following your citation will know based on access date that there may have been edits to your source.
There's really no way to be certain with electronic sources that an article will be identical at different points of time, so you give the best information you can: When it was published, and when you retrieved the cited information.
MLA suggests providing the following information for electronic sources:
Author and/or editor names (if available)
Article name in quotation marks.
Title of the website, project, or book in italics.
Any version numbers available, including editions (ed.), revisions, posting dates, volumes (vol.), or issue numbers (no.).
Publisher information, including the publisher name and publishing date.
Take note of any page numbers (p. or pp.) or paragraph numbers (par. or pars.).
URL (without the https://)
DOI or permalink.
Date you accessed the material (Date Accessed). [EMPHASIS MINE]